A. Field of the Invention
The present invention relates to a method and apparatus for reserving access to bandwidth in a communications channel in a network. More particularly, the invention relates to methods and apparatus for reserving access to bandwidth in a communications channel in a wireless network using asynchronous transactions.
B. Description of the Related Art
As greater demands are placed on network technology, network applications will soon necessitate the reservation of bandwidth for seamless transmissions over a communications channel. Any type of network application that requires large amounts of bandwidth will be a candidate for the reservation of bandwidth. Of course, the most likely type of network applications that will require reserved bandwidth are multimedia applications. Examples of multimedia applications include packet voice and video conferencing. Yet, any network application that requires real-time transactions may require reserved bandwidth.
To provide for a reservation of bandwidth for multimedia and other bandwidth-dependent network applications, some methodology for reserving access to bandwidth on a communications channel will be required, where the reservation may be changed during the operation phase. This capability to accept changes during the operation phase is known as xe2x80x9con-demand, as-desiredxe2x80x9d allocation. Without this capability, the processing of a reservation of access during high bandwidth/low delay communications would be inhibited by other traffic, such as a large file transfer. In particular, for wireless local area networks, cellular networks, and ad hoc networks, the need for reserved access to bandwidth in a communications channel in an on-demand, as-desired manner will be most significant.
Traditional mechanisms for providing access to a communications channel have tended to reside in the framework of fixed or demand assignments using time division multiple access (TDMA). Some of the more common TDMA-based schemes for result access include priority-oriented demand assignment (PODA) and split-channel reservation multiple access (SRMA), which use complex, synchronous techniques. However, the TDMA-based schemes do not allow for the reservation of access to bandwidth over a communications channel in an asynchronous manner.
Another traditional mechanism is code division multiple access (CDMA), which uses a digital spread-spectrum modulation technique. However, because CDMA-based schemes do not readily provide for changing the amount of code allocated, which is needed for reserved access.
Still another traditional mechanism is frequency division multiple access (FDMA), which provides for the allocation of a frequency band to a user. However, like CDMA-based schemes FDMA-based schemes also do not allow for on-demand, as-desired allocation.
For the reasons noted above, CDMA-based schemes and FDMA-based schemes are not suitable for reserved access. Further, there are also problems with the TDMA-based schemes. Yet, because TDMA-based schemes are one of the most common mechanisms for providing access to a communications channel, it should be noted that TDMA-based schemes are also undesirable for reserved access based on several distinct disadvantages and shortcomings.
First, TDMA-based schemes are inadequate for bursty network traffic because the late arrival of a data packet results in the loss of the allocated time slot, a situation very common in bursty network traffic. Accordingly, this situation results from the inability to guarantee or reserve access.
Second, the TDMA-based schemes are also inadequate due to the inefficient allocation of resources. To contend for the possibility of a system failure, a TDMA-based scheme frequently makes excessive resources available in order to avoid failures from bursty network traffic. This failure contingency increases complexity, cost, and overhead for systems using TDMA-based schemes. Furthermore, one of the primary reasons that the TDMA-schemes are so inefficient is that the synchronization between nodes requires substantial additional time.
Third, the TDMA-based schemes are particularly inadequate because they are currently not compatible with the IEEE 802.11 standard. The IEEE 802.11 standard is the most common standard for wireless local area networks (wireless LANs), as established by the Institute of Electrical and Electronic Engineers (IEEE). The IEEE 802.11 standard for wireless LANs specifies an xe2x80x9cover the airxe2x80x9d interface between a wireless client and a base station, as well as among wireless clients. First conceived in 1990, the IEEE 802.11 standard has undergone six drafts, and the final draft was approved on Jun. 26, 1997. Now that IEEE 802.11 has become finalized, the incompatibility of the TDMA-based schemes with this standard will continue to become ever more significant.
Fourth, the TDMA-based schemes are also particularly inadequate because they are difficult to implement with ad hoc networks. An ad hoc network has no base station, and this peculiarity adds to the difficulty of using TDMA-schemes with these networks. This is because TDMA-based schemes require synchronization, and without a base station, synchronization is extremely difficult. This is one of the most significant shortcomings of the TDMA-schemes when used with ad hoc networks.
For the foregoing reasons, the current systems and methodologies reflect an unsatisfactory development of systems and methods for providing access to a communications channel in a network. Accordingly, a need exists for a scheme to provide for the actual reservation of access to bandwidth in a communications channel in a network in an on-demand, as-desired manner. In addition, a need also exists for the reservation of access to bandwidth in a communications channel by asynchronous methodologies.
Methods and apparatus consistent with the present invention overcome the shortcomings of the conventional systems by providing guaranteed access to bandwidth in a communications channel in a network.
In accordance with the purposes of the invention, as embodied and broadly described herein, one aspect of the invention includes a method consistent with the present invention of reserving access to a transmission bandwidth in a communications channel at a terminal in a network. This method comprises transmitting to a server a reservation request to send signal, indicating a request for reservation of transmission bandwidth in a communications channel in the network, receiving a first clear to send signal from the server, transmitting to the server a modified request to send signal, indicating a request for admission to transmit data over reserved bandwidth of a communications channel in the network, receiving a second clear to send signal, and transmitting a data packet to the server.
In another aspect, the invention includes a method of reserving access to a transmission bandwidth in a communications channel at a server in a network. This method comprises receiving from a terminal a reservation request to send signal, representing a request for reservation of transmission bandwidth in a communications channel in the network, transmitting a first clear to send signal to the terminal, receiving from the terminal a modified request to send signal, representing a request for admission to transmit data over reserved bandwidth of a communications channel in the network, transmitting a second clear to send signal, and receiving a data packet from the terminal.
In yet another aspect, the invention includes a method of reserving access to a transmission bandwidth in a communications channel in a network. The method comprises transmitting from a terminal to a server a reservation request to send signal, indicating a request for reservation of transmission bandwidth in a communications channel in the network, receiving at the server the reservation request to send signal, representing the request for reservation of transmission bandwidth in a communications channel in the network, transmitting a first clear to send signal from the server to the terminal, receiving the first clear to send signal at the terminal, transmitting from the terminal to the server a modified request to send signal, indicating a request for admission to transmit data over reserved bandwidth of a communications channel in the network, receiving at the server the modified request to send signal, representing the request for admission to transmit data over reserved bandwidth of a communications channel in the network, transmitting a second clear to send signal from the server to the terminal, receiving the second clear to send signal at the terminal, transmitting a data packet from the terminal to the server, and receiving the data packet at the server.
Additional aspects of the invention are disclosed and defined by the appended claims. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.